how can i insert any <tags> into textarea arond selection

[admin]

i have some problem please help if you can

i have one textarea, and user can type his info into this area
i make some buttons, that user can format his text
(like in this forum)

but here it is made so, that you need to write text into open.window

i want that tags will be insert by clicking button around any selection, and then shown in the same textarea already formated